It is a situation which a salesperson announces to a group of people to attract them to buy his goods
Here is the full sentence.
ああいう物{もの}の値{ね}うちのわかる決{けつ}断{だん}力{りょく}さえた少{しょう}年{ねん}が日{に}本{ほん}にいるっていうことはだ
Actually, there are 3 text bubbles adjacent to each other in the same panel and I brought only the sentence from the last bubble into the above line.
Below here are the 2 first sentences from those bubbles.
First bubble: いや おそれ いりました!
Second bubble: これだけいる おとなどもが買{か}いしぶって いる中{なか}で あんな子{こ}どもが さっと こづかい はたくなんざ じつに 見{み}上{あ}げた もんですよ